package com.xs.mvc.lock;

import java.util.Collections;

import redis.clients.jedis.Jedis;

/**
 * @Title: <P>RedisLock.java</P>
 * @Package <P>com.xs.mvc.cache</P>
 * @Description: <P>redis 分布式锁</P>
 * @author renweiping
 * @date 2019年2月18日 上午10:15:30
 * @version 1.0
 */

public class RedisLock {
	    private static final String LOCK_SUCCESS = "OK";
	    private static final String SET_IF_NOT_EXIST = "NX";
	    private static final String SET_WITH_EXPIRE_TIME = "PX";
	    
	    private static final Long RELEASE_SUCCESS = 1L;
	    /**
	     * 尝试获取分布式锁
	     * @param jedis Redis客户端
	     * @param lockKey 锁
	     * @param requestId 请求标识
	     * @param expireTime 超期时间
	     * @return 是否获取成功
	     */
	    public static boolean tryGetDistributedLock(Jedis jedis, String lockKey, String requestId, int expireTime) {
	 
	        String result = jedis.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_TIME, expireTime);
	 
	        if (LOCK_SUCCESS.equals(result)) {
	            return true;
	        }
	        return false;
	 
	    }
	    
	    
	    
	    
	    /**
	     * 释放分布式锁
	     * @param jedis Redis客户端
	     * @param lockKey 锁
	     * @param requestId 请求标识
	     * @return 是否释放成功
	     */
	    public static boolean releaseDistributedLock(Jedis jedis, String lockKey, String requestId) {
	 
	        String script = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end";
	        Object result = jedis.eval(script, Collections.singletonList(lockKey), Collections.singletonList(requestId));
	 
	        if (RELEASE_SUCCESS.equals(result)) {
	            return true;
	        }
	        return false;
	 
	    }
	    
	    
}
